Roguelock Elven Accuracy Versus Dex ASI Help

[Mutsden]

Hi all,

I'm currently playing a melee focused Rogue 2/Chainlock 3 with intent to go Swashbuckler X/Chainlock 3. Since I expect I will frequently have a source of advantage, I was considering taking the Elven Accuracy feat at some point. My question is, at what point would it be beneficial to take the feat rather than a dex ASI given advantage in both scenarios?

Some relevant character information:
Half-elf
Dex 16
AC 14
Armed with rapier and light xbow
Frequent sources of advantage: darkness/devil's sight, familiar help action, party members' spells
Using darkness and mirror image combo to try to avoid being hit

It has been a long time since my probability/statistics course so any advice will be appreciated. Thanks! :smallsmile:

[Man_Over_Game]

Hi all,

I'm currently playing a melee focused Rogue 2/Chainlock 3 with intent to go Swashbuckler X/Chainlock 3. Since I expect I will frequently have a source of advantage, I was considering taking the Elven Accuracy feat at some point. My question is, at what point would it be beneficial to take the feat rather than a dex asi given advantage in both scenarios?

Some relevant character information:
Half-elf
Dex 16
AC 14
Armed with rapier and light xbow
Frequent sources of advantage: darkness/devil's sight, familiar help action, party members' spells
Using darkness and mirror image combo to try to avoid being hit

It has been a long time since my probability/statistics course so any advice will be appreciated. Thanks! :smallsmile:

You should probably grab the feat as early on as possible. It already provides a +1 into any "elf" stat of your choosing, and it dramatically improves your chance of a critical hit, which applies to your Sneak Attack bonuses.

2d20 (advantage) roughly is a +5 increase to your roll. 3d20 is about another +2.5 (assuming you don't crit). So your to-hit is going to be roughly a +6 from bonuses and +7.5 from roll statistics, so your average will be about a 23.5 on your attack rolls. So you're not going to miss, EVER.

Increasing Dex directly will increase your AC, skills, and damage, so it's really only relevant before Elven Accuracy if you're being attacked constantly. Damage is reliant more on Sneak Attack than your standard damage, and a +1 to Dex skills isn't a big enough deal to consider when you already have Expertise in them.

[Keravath]

You didn't mention what sort of warlock ... this is a factor in case hexblade's curse is a consideration.

1) Crits

Advantage probability of crit = 1 - (19/20)**2 = 9.75%
Tri-vantage probability of crit = 1 - (19/20)**3 = 14.3%

2) To hit vs a target of X (X = AC-to hit modifier)

Avantage = 1 - ((X-1)/20)**2
Tri-vantage = 1 - ((X-1)/20)**3

Examples AC=15, to hit mod = +5, X = 10 (or AC=18, to hit = +8 etc)

Advantage = 79.8%
Tri-vantage = 90.9%

The chance to MISS in this case are Advantage ~20% and Tri-vantage ~10% ... so for a middle of the road target number having elven advantage roughly halves your chance of missing (though it was somewhat small to begin with).

Two more examples:

AC20, to hit = +5, X=15 (or AC 23, to hit = +8 etc)
Advantage = 51%
Tri-vantage= 65.8%
Miss chance goes from about 1/2 to 1/3

AC10, to hit = +5, X=5 (or AC=13, to hit = +8 etc)
Advantage = 96%
Tri-vantage = 99.2%
You were probably going to hit in both cases :) but tri-vantage makes hitting much more likely.

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So comparing strictly advantage to tri-vantage ... the Elven Accuracy will make it more likely that you will hit and about 50% more likely to get a crit.

But your comparison is really to a case of +2 to dex vs +1 to dex (which does nothing) and elven accuracy.

In that case

Examples AC=15, to hit mod = +5, X = 10 (or AC=18, to hit = +8 etc)
Hit mod = +6 with advantage X = 9
84%
vs hit mod = +5 with tri-vantage X = 10
90.9%

So elven accuracy still works out better in terms of hitting IF you have advantage.

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However, this depends on how often you can obtain advantage. You have a good build giving a number of different mechanisms but when you don't have advantage, the +2 dex will add to your to hit making you more likely to land sneak attacks. Also, the +2 to dex increases your AC ... which is particularly low for a character planning on being close to melee ... your initiative and your saving throws and skills checks.

With an even dexterity score, I would say that you get a lot more mileage out of the +2 dex ASI rather than elven accuracy. This is especially true since you will want to maximize your dexterity at some point with a rogue. Taking elven accuracy in dex leaves you with a 17 which is still going to take two more ASI/feats to max out. (On the other hand it can be fun rolling all the d20s when the opportunity comes up).

One more thing .. if you happen to have an odd charisma score (which you probably don't seeing that you are a half-elf) you could use elven accuracy to boost your charisma ... it still applies to all attacks you make with dex, int, wis or cha. Boosting cha helps a swashbuckler in several ways.

However, if you don't have an odd stat then I think some of the other choices are probably more valuable.

[Mutsden]

Thank you for the insights and thorough breakdown of the numbers.


You didn't mention what sort of warlock ... this is a factor in case hexblade's curse is a consideration.
Sorry about that. I went GOO for the flavor/social interaction components (think "Indiana Jones and the Mountains of Madness"), but I can definitely see how the improved crit/proficiency damage would be a fun interaction with the feat. Something to consider in the future...

I still have 2 levels to go before I reach my first ASI :smallannoyed: so I think I'll try to keep track of how often I actually have advantage and decide from there. The allure of rolling more d20s is pretty strong though...

Thanks again.